- -9

     "- " 4 ()
     "- " 4 (c  4 )
     "- " 6 ()
     "- " 6 (c  4 )
     "- " 8 ()
     "- " 8 (c  4 )
     "- " 10 ()
     "- " 10 (c  4 )
    %
    ( )